According to the increase in demands for large-capacity data transmission, for example, a transmission device of a digital coherent optical transmission scheme for enabling transmission at 100 (Gbps) or more with one wavelength light is used. As an optical transmission and reception module corresponding to the digital coherent optical transmission scheme, there is, for example, 100 gigabit form-factor pluggable (CFP)2-analog coherent optics (ACO).
The optical transmission and reception module of this type is detachably connected to, via an electric connector, a host module included in a transmission device body. In the host module, a compensation circuit such as an equalizer (see, for example, Japanese Laid-open Patent Publication Nos. 10-327209 and 2005-347916) is provided to compensate for deterioration of signals input and output between the host module and the optical transmission and reception module via the electric connector.
A filter coefficient of an electric filter such as a finite impulse response (FIR) filter configuring the equalizer is adjusted, for example, during manufacturing of the host module, in a state in which the host module is connected to an optical transmission and reception module for inspection.
However, a transmission characteristic of the signals input and output between the host module and the optical transmission and reception module is different depending on not only a combination of module types of the host module and the optical transmission and reception module but also a combination of individual characteristics of the host module and the optical transmission and reception module due to fluctuation during the manufacturing. For example, a skew of a signal changes according to the length of a wire for the signal passing the electric connector.
Therefore, depending on a combination of the host module and the optical transmission and reception module connected to each other, it is likely that a signal transmission characteristic does not satisfy a predetermined standard because the adjusted electric filter is inappropriate.